pojo-fluent-validator
v1.1.7
Published
Validation and conversion tool for plain old javascript objects.
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pojo-fluent-validator
pojo-fluent-validator
is javascript library used to check and convert plain old javascript objects with fluent configuration syntax.
NOTE: Validator works with plain old javascript objects only. That means no classes, no functions, no prototypes - it works with object literals, primitive types and arrays. Validator doesn't change source object, instead it makes a copy of the object but doesn't call constructor and don't copy prototype.
Features
- Validates and converts primitive types - numbers, strings, and any type - with custom validation rule.
- Validates objects by validating each object property.
- Validates hashes (maps) - objects where each property value has the same structure.
- Validates arrays of primitive types or objects.
- Composability - validators for complex objects uses regular validators, so nested value can be object, array, hash or primitive type.
- Fluent syntax - validation rules are configured using chained method calls.
Usage
Installation
npm install pojo-fluent-validator
NOTE: validate
function which returns a promise is not included in package, it looks like:
Javascript
import { validate as validateWithCallback } from "pojo-fluent-validator";
export function validate(value: any, ...validators) {
if (!validators || !validators.length) {
throw new Error("At least one validator is required");
}
return new Promise((resolve, reject) => {
validateWithCallback(
value,
(errors, result) => {
if (errors) {
reject(errors);
}
else {
resolve(result);
};
},
...validators);
});
}
Typescript
import { validate as validateWithCallback, ValidationRule } from "pojo-fluent-validator";
export function validate<T>(value: any, ...validators: ValidationRule<T>[]): Promise<T> {
if (!validators || !validators.length) {
throw new Error("At least one validator is required");
}
return new Promise((resolve, reject) => {
validateWithCallback(
value,
(errors, result) => {
if (errors) {
reject(errors);
}
else {
resolve(result);
};
},
...validators);
});
}
Single value validation example.
import { rules } from "pojo-fluent-validator";
const rule = rules.num().must(v => v > 0, { errorMessage: "Must be greater than zero!" });
validate("10", rule).then(v => {
// Value successfuly converted to number and validated
console.log(v, v + 2); // Outputs 10 12
}).catch(err => {
// Don't reach this point until value is invalid.
});
validate("sdf", rule).then(v => {
// Value is invalid number, then block is not executed
).catch(err => {
// err[""] contains validation messages for whole object
console.log(err[""]); // Outputs ["Value is not a valid number"]
});
Object validation example. Shows validator composability.
import { rules } from "pojo-fluent-validator";
const positiveNumberRule = rules.num().must(v => v > 0);
const productRule = rules.obj({
// Use previously defined rule
id: positiveNumberRule,
// Or inlined rule
title: rules.str().notEmpty(),
// Rule can be extended with additional conditions using fluent syntax.
// .required() call need to fail on null values. Number validator by default passes nulls.
vendorPrice: positiveNumberRule.required(),
// Second parameter of `must` rule is validating object
// Inside .must(..) check we don't assume retailPrice can be null.
// That's because required() rule stop rule chain on fail.
// To control this use { stopOnFailure: false } as rule options.
retailPrice: positiveNumberRule.required()
.must((v, product) => product.retailPrice > product.vendorPrice,
{ errorMessage: "Product should be profitable" })
});
// Valid object
validate({
id: 1,
title: "Melon",
// rules.num() parses number by default.
vendorPrice: "12.3",
retailPrice: 14.44
}, productRule).then(p => {
// Product successfuly validated
// p.vendorPrice is now number.
console.dir(p);
}).catch(err => {
// Don't reach this point until value is invalid.
});
// Valid object
validate({
id: 1,
title: "Melon",
// rules.num() parses number by default.
vendorPrice: "12.3",
retailPrice: 4.44
}, productRule).then(p => { })
.catch(err => {
// err is hash of "path.to.error.property.or[index]": ["validation", "messages"]
console.log(err["deliveryPrice"]); // Outputs ["Product should be profitable"]
});
Array validation
import { rules } from "pojo-fluent-validator";
const numArrayRule = rules.arr(
rules.num().required().must(v => v > 0));
validate([1, 2, "3"], numArrayRule)
.then(arr => {
// Array validated. Third element converted from string.
console.log(arr); // Outputs [1, 2, 3]
});
validate([1, 2, "three"], numArrayRule)
.catch(err => {
// For arrays error path is "[2]"
console.log(err["[2]"]); // Outpus ["Value is not a valid number"]
});
Array of objects validation
import { rules } from "pojo-fluent-validator";
const objArrayRule = rules.arr(
rules.obj({
id: rules.num().required(),
title: rules.str().required()
}).required() // rule.obj passes null values by default
.expandable() // Expandable object allows to have extra non-validatable properties
);
const invalidArray = [{
id: 1,
title: "First"
}, {
id: null,
title: "Second"
}];
validate(invalidArray, objArrayRule)
.catch(err => {
// Rules pathes are nested in the way of plain javascript access operations
console.log(err["[1].id"]); // Outputs ["Value is required"]
});